Some 4 lane undivided roads being converted to 3 lane with a center turn lane

[peterj920]

Seems like 3 lane roads are becoming more common than 4 lane undivided.  Some cities are even re-striping some roads and converting them from 4 lane to 3 lane.  I prefer 4 lanes over 3 lane roads because I'm less likely to be stuck behind a slow driver on a 4 lane road, and I since I can't pass on a 3 lane road, I can't do anything about being behind a slow driver.  I can understand why some cities are doing this.  They want to keep traffic moving by allowing people turning left to use the center lane, but keep traffic slower by not allowing anyone to pass.  I would counter argue that 3 lane roads can't handle the same capacity as a 4 lane road, and if an area sees an increase in traffic, the 3 lane road is going to end up congested because it doesn't have the same capacity.  If there is a stop at a traffic signal or roundabout (I live near a roundabout that gets very backed up on a 3 lane road during peak times), having only one lane really backs up traffic.  If another lane would have been added and the roundabout would be constructed with another lane, the backups would be cut in half.  15-20 years ago, most cities seemed to just build a 4 lane road and not consider 3 lanes, which I think are a lot better.  Thoughts?

[SD Mapman]

I think a lot of it has to do with there not being that much of an improvement in traffic with a 4-lane versus a 3-lane, and as such DOTs will take the cheaper option (the 3-lane).
SDDOT did a study on this for a corridor in Spearfish: http://www.sddot.com/transportation/highways/planning/specialstudies/us14a/FinalReport_NoAppendices.pdf (pages 51 & 55 have the relevant info)

This is South Dakota, however, so make of that what you will.

[jakeroot]

A lot of Seattle's four lane roads are being switched to three or two lanes to incorporate parking and bike lanes.

In Vancouver, many of the suburban arterial roads are four lanes. I'm not aware of too many that have switched to three lanes, which is nice because I also prefer four to three, if only so I can overtake slower traffic. But, taking into account an increase in cycling traffic, I can certainly understand the switch from four to three.

[peterj920]

I think a lot of it has to do with there not being that much of an improvement in traffic with a 4-lane versus a 3-lane, and as such DOTs will take the cheaper option (the 3-lane).
SDDOT did a study on this for a corridor in Spearfish: http://www.sddot.com/transportation/highways/planning/specialstudies/us14a/FinalReport_NoAppendices.pdf (pages 51 & 55 have the relevant info)

This is South Dakota, however, so make of that what you will.

The roads that are being converted from 4 to 3 lanes are using the same exact roadway, and only the striping is being changed.  Cost has nothing to do with that.  I have a streetview picture of Franklin St in Appleton, WI of a 3 lane road where you can see that it was 4 lanes with the old markings that were ground off.  I know South Dakota is converting roads down to 3 lanes.  I was in Milbank, and US 12 was 4 lanes through town, now it's 3. 


https://www.google.com/maps/@44.2640413,-88.4130765,3a,90y,85.73h,65.96t/data=!3m6!1e1!3m4!1s6DmQnqJh7JR7ck3LGI4jgA!2e0!7i13312!8i6656?hl=en

[NJRoadfan]

The conversion is commonly called a "street diet". Its becoming more common in urban areas and allows for bike lanes and safer pedestrian crossings.

[1995hoo]

The conversion is commonly called a "street diet". Its becoming more common in urban areas and allows for bike lanes and safer pedestrian crossings.

A street near our neighborhood was recently restriped as part of a "road diet" when it was repaved this summer. The previous four lanes were more than was needed for the traffic the road carried and it was restriped as two lanes, two bike lanes, and left-turn lanes where needed (not a TWLTL). So far the people who have complained are the ones who were always going 50 to 55 mph (speed limit was, and remains, 35 mph)–they seem to be offended when they come up behind people like me who set the cruise control at about 38 to 40 mph.

It makes sense to me when a road is genuinely overbuilt for the traffic it carries.


(Edited a day after posting due to a typo that changed the meaning of what I wrote)

[Mergingtraffic]

I don't mind a 4-lane road converted to a 3-lane road with center turn lanes IF there are a lot of left turns made by vehicles for major traffic generators such as strip malls etc.  and, the amount of left-turns impede traffic flow.

Reason: If there is NO left turn lane then you have to people abruptly changing from the left to the right to avoid the left-turning person.  You also have more rear-end crashes of somebody bumping into a left-turning vehicle. Sometimes giving left-turning vehicles their own lane will help traffic flow.

With that said....

If they convert a 4-lane road to a 3-lane road for parking or bike lanes...THAT I have a problem with b/c you are doing it for reasons other than traffic flow. I have never seen an area where bikes outnumber other vehicles. 

[PHLBOS]

MacDade Blvd. between South Ave. and just west of Oak Ave. in Glenolden, PA went through a similar 4-lane to 3 (center lane/left-turn) diet a few years ago.  In most instances, the extra space was just a narrow shoulder on either side with one stretch slightly shifted for on-street parking along some storefronts.

[cl94]

Road diets certainly aren't a new thing. A bunch have been occurring in New York lately, quite notably near Buffalo. Buffalo has instituted a "complete streets" policy for major rehabs and new construction that requires the inclusion of facilities friendly to bicyclists and pedestrians. Just about every mill and fill project in the city in recent years has added bike lanes. In the case of 4 lane undivided streets, they are being restriped to 3 lanes when resurfaced, featuring bike lanes (always) and full-time parking lanes (on both sides of street where space allows, else only one side). Almost every 4-lane street within the city limits would function better as 2 lanes with a center turn lane and dedicated parking lanes, as traffic volumes are relatively low.

Diets are planned for NY 266, the remainder of Broadway/former NY 130 west of US 62 that has not been dieted, and NY 5 between NY 33 and NY 198. In the case of the latter, 6 lanes would be reduced to 4-5 with 1-2 permanent parking lanes and bike lanes. A center turn lane would be present along the entire length, but there is debate as to whether or not one direction should only have one general-purpose lane in exchange for full-time parking. The NY 266 diet will include transit priority at signals and possible BRT service.

[hbelkins]

The "road diet" for US 127 in downtown Harrodsburg, Ky., has really helped traffic flow there. Previously the route was four lane undivided. Traffic in the left lane would frequently get backed up when it had to stop for a driver turning left into a business, residence or side street. Converting it into a two-lane with a center turn lane was a major improvement.

Of course having a four-lane bypass around town took a lot of the thru traffic out of downtown, but it was still busy enough to have traffic stopped so a driver could turn left turn into a nuisance.

[Brian556]

Four-lane undivided streets without left turn lanes are pure crap to begin with.

[Rothman]

The conversion is commonly called a "street diet". Its becoming more common in urban areas and allows for bike lanes and safer pedestrian crossings.

Eh, not in all cases.  In New York, we have roads that were painted for four lanes that really never should have been.  I attended a meeting some time ago where conversions to three lanes (two lanes + suicide lane) were argued to have increased the efficiency of the facilities re-painted as such.

So, it's not all about the peds and bikes.

[dgolub]

New York City has been doing this in a lot of places.  Last summer, I attended a presentation by NYCDOT about their plans for West End Avenue in Manhattan.  Part of the logic behind it is that the area between the two directions can be used to go around double-parked cars without having to wait for oncoming traffic.  It also serves as a safe zone where pedestrians can wait to finish crossing the street.  They did it on the cross street where I live, and I must say it's much easier to cross the street now.

[jeffandnicole]

In my general area, we've had two road diets take place recently.

In the first, it was converted from 4 to 3 lanes, with the addition of bicycle lanes.  Parallel parking always existed.  The area is a downtown area that has seen many businesses close up over the years, and they figured this road diet would assist in revitalizing the area, encourage thru traffic to find other ways to get around, and thus would encourage mostly locals wanting to shop to use the road.Many arguments included that since people would be forced to drive slower, it would create an opportunity to window shop, which would encourage businesses to open.  As stupid as that sounds....oh, wait, it was stupid.  There's probably fewer businesses operating today than there was prior to the road diet.  While it does assist with left turning traffic, because less traffic can get thru the area with only a single thru lane, they had to increase the timing of the lights for the main road, causing some of the side roads to suffer increased congestion.   Oh, and bicyclists are few and far in-between.  About the only positive is that people don't try to cut from the left lane to the right lane to avoid vehicles trying to turn left.  But for all the excuses reasons why this road diet would revitalize the area, none have actually happened.

I should note that at least they kept the road diet to the downtown area.  They originally wanted to extend it out further to a higher speed area, but decided against it.

Another road diet is on NJ 168, between 295 & near "I-76C" (the connector ramps to the Walt Whitman Bridge).  Even though the speed limit is 40 mph, it's the rare case where traffic is almost always travelling below the speed limit.  But overall, it doesn't have any business or traffic issues, other than slow traffic.

[cl94]

The conversion is commonly called a "street diet". Its becoming more common in urban areas and allows for bike lanes and safer pedestrian crossings.

Eh, not in all cases.  In New York, we have roads that were painted for four lanes that really never should have been.  I attended a meeting some time ago where conversions to three lanes (two lanes + suicide lane) were argued to have increased the efficiency of the facilities re-painted as such.

So, it's not all about the peds and bikes.

I was at a conference 2 weeks ago where a few people from the Buffalo DPW said the diets around here are mainly for bikes and peds. They just happened to have a higher LOS.

[Rothman]

The conversion is commonly called a "street diet". Its becoming more common in urban areas and allows for bike lanes and safer pedestrian crossings.

Eh, not in all cases.  In New York, we have roads that were painted for four lanes that really never should have been.  I attended a meeting some time ago where conversions to three lanes (two lanes + suicide lane) were argued to have increased the efficiency of the facilities re-painted as such.

So, it's not all about the peds and bikes.

I was at a conference 2 weeks ago where a few people from the Buffalo DPW said the diets around here are mainly for bikes and peds. They just happened to have a higher LOS.

Bikes and peds...in Buffalo...where winter lasts at least 9 months out of the year...

[SD Mapman]

Eh, not in all cases.  In New York, we have roads that were painted for four lanes that really never should have been.  I attended a meeting some time ago where conversions to three lanes (two lanes + suicide lane) were argued to have increased the efficiency of the facilities re-painted as such.

Yup. It doesn't make sense to me, but I guess that's just how the cookie crumbles.

[vdeane]

Albany is getting into complete streets, so I wouldn't be surprised if we see a lot more road diets around here in the future.  CDTC likes them too.

And yes, the fact that they trap cars behind slowpokes is considered a feature rather than a bug.

I believe NYSDOT policy is to investigate them for roads with AADTs less than 15k.

[doorknob60]

Depends on the road. For major through arterials that get a good amount of traffic, it's probably not a good idea. But for minor arterials or collectors serving more local traffic (but are still important roads), I can get behind it. One example of a road that this would be good for is Colorado Ave in Nampa.

Picture (click for Google Maps):


This is a 4 lane, 35 MPH street with no bike lanes or center turn lane. It gets a moderate amount of traffic, but not a lot (the number of cars you see on the satellite view gives a good general idea of mid-day non rush hour traffic). I think adding bike lanes and 2 car lanes plus a center turn lane would be beneficial. A lot of people are making left turns to the college dorms and other nearby apartments, and a center left turn lane would be better than having to move over to the right lane to pass. There's just not enough traffic to make 4 lanes useful. I never need to pass people on this road (except when they're turning), and almost everybody obeys the (very reasonable) 35 MPH speed limit.

They should also add a crosswalk around what Google calls Juniper St. (it's not actually a named street), as a lot of college students cross there to get from those dorms to campus. The traffic is low enough that you can safely do it, but a crosswalk would be nice.

I don't think Nampa has plans to road diet this road though. They're currently rebuilding an outdated section of this road to the east of here (from Chestnut to Southside), and are upgrading the 2 lane, no bike lanes, no turn lane road into 4 lanes (presumably a similar road to the one pictured above). I think the 2 lanes + center lane + bike lane solution would be better for this road, but this is Nampa, not Bend. The rebuilt road will be miles better than the old one though, so I can't complain. Except about how long it's been closed! Construction is not supposed to be finished until late 2016, and the road has been closed for over a year now I think, and the nearest detour is at Greenhurst, pretty far out of the way. This is the kind of project where I'd hope they wouldn't have to close the road for more than a few months, it's taking too damn long. After the project is finished, I do expect traffic to increase over the whole stretch though, so maybe the 4 lanes will be a better fit then.

[swbrotha100]

I've seen this treatment given to some roads in the Tucson and Phoenix areas.

[1995hoo]

....

And yes, the fact that they trap cars behind slowpokes is considered a feature rather than a bug.

....

It might be a feature, depending on what the speed limit is and how fast the so-called "trapped" cars were going. On the 35-mph street near our neighborhood I mentioned earlier, prior to the road being restriped there was more than one incident with people going in excess of 70 mph (and one of those people managed to lose control and slam into the brick wall fronting one of the neighborhoods). I haven't heard of any of that sort of thing since the "road diet" was completed.

[PHLBOS]

This one's a bit more drastic (4-lane divided converted into 2-lane undivided).  This change took me by surprise when I drove it last year (after not venturing by there in a couple of years).

In Ridley Park, PA; a portion of Sellers Ave. where it crosses under I-95 now carries 2-lanes of traffic for both directions in the former-northbound-only lanes.  A portion of the former 2 southbound lanes south of the I-95 overpass is now completely gone.

[jakeroot]

This one's a bit more drastic (4-lane divided converted into 2-lane undivided).  This change took me by surprise when I drove it last year (after not venturing by there in a couple of years).

In Ridley Park, PA; a portion of Sellers Ave. where it crosses under I-95 now carries 2-lanes of traffic for both directions in the former-northbound-only lanes.  A portion of the former 2 southbound lanes south of the I-95 overpass is now completely gone.

That's definitely not common (in fact, I don't think I've ever seen an entire carriageway demolished -- usually, the sidewalks are just widened and some parking stalls and a cycle tracks are installed). But, I do like what I see. Looks like a "friendlier" road now.

[Buffaboy]

The conversion is commonly called a "street diet". Its becoming more common in urban areas and allows for bike lanes and safer pedestrian crossings.

Eh, not in all cases.  In New York, we have roads that were painted for four lanes that really never should have been.  I attended a meeting some time ago where conversions to three lanes (two lanes + suicide lane) were argued to have increased the efficiency of the facilities re-painted as such.

So, it's not all about the peds and bikes.

I was at a conference 2 weeks ago where a few people from the Buffalo DPW said the diets around here are mainly for bikes and peds. They just happened to have a higher LOS.

This is the flawed logic that will destroy the 198 (although I tend to wish Utica at least had bike lanes on a couple thoroughfares).

[mgk920]

I think a lot of it has to do with there not being that much of an improvement in traffic with a 4-lane versus a 3-lane, and as such DOTs will take the cheaper option (the 3-lane).
SDDOT did a study on this for a corridor in Spearfish: http://www.sddot.com/transportation/highways/planning/specialstudies/us14a/FinalReport_NoAppendices.pdf (pages 51 & 55 have the relevant info)

This is South Dakota, however, so make of that what you will.

The roads that are being converted from 4 to 3 lanes are using the same exact roadway, and only the striping is being changed.  Cost has nothing to do with that.  I have a streetview picture of Franklin St in Appleton, WI of a 3 lane road where you can see that it was 4 lanes with the old markings that were ground off.  I know South Dakota is converting roads down to 3 lanes.  I was in Milbank, and US 12 was 4 lanes through town, now it's 3. 


https://www.google.com/maps/@44.2640413,-88.4130765,3a,90y,85.73h,65.96t/data=!3m6!1e1!3m4!1s6DmQnqJh7JR7ck3LGI4jgA!2e0!7i13312!8i6656?hl=en

Four lanes was definitely overkill on that street and traffic backing up while waiting to turn left into the Post Office parking lot was a real problem.  I consider that restriping to be an improvement.

(I live about 5 blocks south of there.)

There are many other streets in and around the city that would be similarly improved by such restriping.

Others in the Appleton area that have also been so redone include WI 96 between Ballard Rd (County 'E') in Appleton and central Little Chute and Green Bay Rd between Winneconne Ave (WI 114) and Cecil St in Neenah.

Mike